[Sailor Steve]

According to reports, there were many factors contributing to the loss of Britannic, including such minor but avoidable things as the nurses leaving portholes open to ventilate the lower decks. Silly, but you never know.

As for the differences between Britannic and Bismarck, I don't know how hitpoints work in the game, but there are major differences. For a WW2-era battleship things are different. The armored belt is all but useless against torpedoes, first because despite being hardened armor where an underwater blast of that sizes is concerned it's just plain old steel, and second because the armor belt is heavy and its size has to be limited, so normally torpedoes can pass under it. Battleships carried special anti-torpedo bulges below the armor belt, which were designed to be frangible, and for the most part they did a pretty good job. Once hit they became useless against another hit at that same point, but that was unlikely. Yamato was observed to take two hits at the same point, the second of which damaged one of the engine rooms, so it could happen.

Ocean liners had nothing like that.